Server push with Javamail: idle() blocks

Question

Hi,
today I tried to implement server push functionality in my mail application via Javamail.
I did this by calling the following method everytime Javamail creates a new Folder instance for me:
private void activateServerPush(Folder f) {
     if (f instanceof IMAPFolder) {
          final IMAPFolder ifo = (IMAPFolder) f;
          ifo.addMessageCountListener(new MessageCountListener() {
               @Override
               public void messagesAdded(MessageCountEvent arg0) {
                    DebugPrinter.print(this, "messagesAdded event called");
                    clear(false, true); // Clear cache
                    onMessageCountChanged();
               @Override
               public void messagesRemoved(MessageCountEvent arg0) {
                    DebugPrinter.print(this, "messagesRemoved event called");
                    clear(false, true); // Clear cache
                    onMessageCountChanged();
          MyThread thread = new MyThread() {
               @Override
               public void run() {
                    while (true) {
                         DebugPrinter.print(this, "Before idle");
                         try {
                              ifo.idle();
                              DebugPrinter.print(this, "After idle");
                         } catch (MessagingException e) {
                              // TODO Auto-generated catch block
                              e.printStackTrace();
                         DebugPrinter.print(this, "After idle try");
          // Start thread
          ServletThread.EXECUTOR_SERVICE.submit(thread);
}Now, when I run the code above, I only get "Before idle" as output.
The rest won't be printed so it seems like idle() is blocking.
Also, the event listener messagesAdded(...) are not called. I tried this by sending an email to myself but nothing happens.
What's wrong?

Answer 1

Hi Bill and thanks for your reply.
How does the idle command (line) look line in the debug output?
I simply did a full text search for the word "idle" (ignore case) of everything that got printed to console and only found this:
DEBUG: mail.imap.minidletime: 10
* CAPABILITY IMAP4rev1 LITERAL+ SASL-IR LOGIN-REFERRALS ID ENABLE SORT SORT=DISPLAY THREAD=REFERENCES THREAD=REFS MULTIAPPEND UNSELECT IDLE CHILDREN NAMESPACE UIDPLUS LIST-EXTENDED I18NLEVEL=1 CONDSTORE QRESYNC ESEARCH ESORT SEARCHRES WITHIN CONTEXT=SEARCH LIST-STATUS AUTH=PLAIN AUTH=LOGIN
A2 OK [CAPABILITY IMAP4rev1 LITERAL+ SASL-IR LOGIN-REFERRALS ID ENABLE SORT SORT=DISPLAY THREAD=REFERENCES THREAD=REFS MULTIAPPEND UNSELECT IDLE CHILDREN NAMESPACE UIDPLUS LIST-EXTENDED I18NLEVEL=1 CONDSTORE QRESYNC ESEARCH ESORT SEARCHRES WITHIN CONTEXT=SEARCH LIST-STATUS] Logged in
Also, I noticed that the line "Before idle" (See source code in my initial posting here) gets printed but AFTER that line I can't find anything else that could refer to the idle command.
When I leave Apple Mail (my default native email client on my computer) open, the email that I sent gets correctly (instantly) pushed.